The dangers to carpenters, shinglers, painters and the like while working on sloping and other roofs are generally known. These workers assume various positions on a roof and can easily fall either on the roof or from the roof if sufficiently gripping shoe means are not utilized. Roofers and the like not only work in various positions on the roof, but also must go back and forth between the roof and the ground surface to do their jobs. Thus, the shoes that they wear must be suitable for different types of surfaces and must be constructed so that the gripping effectiveness is not impaired by either upward an downward movement or the numerous travels between the different types of surfaces encountered. Hence, a gripping surface that uses a "sticky" adhesive is not practical. A suction cup arrangement does not work well either because of the graininess of the asphalt.
Asphalt roof shingles, as manufactured by Owen's Corning and Georgia Pacific, for example, are widely used in present-day roof constructions. These roof shingles are generally formed having various grades of stone gravel embedded in a sheet of petroleum-based, marginally flexible material. The embedded gravel is provided in fine, medium and course grains. Therefore, a need exists for a roofer's shoe suitably formed to grip the various granular surfaces of asphalt roof shingles.
The anti-slip footwear of the prior art has been directed to gripping problems associated with wet or slippery ground, slippery underwater rocks, wet or greasy floors, icy and snowy sidewalks and streets and the aforementioned problems encountered by roof workers.
Exemplary of the underwater wet rocks, wet ground and greasy floor anti-slip footwear are U.S. Pat. No. 3,574,958 to Martuch, U.S. Pat. No. 1,490,107 to Hale, and U.S. Pat. No. 2,193,943 to Shea. The Hale patent discloses the use of knobby alligator skin to form the sole of a shoe. In the Shea patent the sole of the shoe is constructed having longitudinally and transversely extending grooves formed in fabric-reinforced vulcanized rubber.
U.S. Pat. No. 2,258,322 to Frolich discloses an anti-skid shoe attachment having a cloth member integrally formed with elastic bands to prevent accumulation of snow and ice particles. U.S. Pat. No. 2,547,812 to Carabatsos discloses a canvas-soled anti-slip footwear attachment, the cross ribs or corrugations of the canvas providing the effective anti-slip surface. A further anti-slip footwear attachment useful on icy streets is disclosed in U.S. Pat. No. 4,372,056 to Benaquista comprising a ribbed non-skid half sole attachable to a shoe by elastic straps.
Martuch is noteworthy in that it discloses the use of indoor-outdoor carpeting as an underwater sole because of its nonwettable, nonwater-retaining properties. However, Martuch does not suggest any advantage in an unsubmerged situation or in a situation such as a grainy surface where it would be expected that the carpet on an inclined surface would exert a vector force sufficient to dislodge surface grains rather than supply an extraordinary synergistic gripping power.
Roofer's shoes and shoe attachments disclosed in the prior art generally comprise a complex structure and are unsuitable for travel back and forth between the roof and the ground surface. In U.S. Pat. No. 987,054 to Eves a roofer's shoe is disclosed having pointed spurs extending downwardly at an acute angle from the flanges, heel and sole of the shoe. U.S. Pat. No. 1,070,951 to Elliott discloses a roofer's shoe attachment made adjustable to various shoe sizes and shapes by the combination of a plurality of segmented plates, each plate having a series of downwardly-extending teeth formed therein. U.S. Pat. No. 1,103,108 to Van Wie discloses a roofer's shoe having a shoe sole formed by a plurality of spikes or other protuberances extending downwardly from a flexible steel sheet plate. And, in U.S. Pat. No. 2,628,437 to Forsythe an anti-slip shoe attachment is disclosed having a sole formed from a flexible sheet of course-grained abrasive material.
While the various anti-slip shoes and shoe attachments of the prior art provide some degree of safety from accidental falls, these devices are unsuitable for working on inclined asphalt roof shingles. Furthermore, the devices of the prior art do not provide an appropriate shoe sole surface suitable for wear on concrete ground surfaces as well on roofs. Also, the invasive gripping means of some of the prior art devices would destroy the asphalt roof shingles widely used in modern-day roof constructions.